Tire with grooves having variable depth

ABSTRACT

A tire includes annular beads, a body ply extending between the annular beads, and a circumferential belt disposed radially outward of the body ply. The tire further includes a circumferential tread disposed radially outward of the circumferential belt. At least three circumferential grooves divide the tread into two outer circumferential ribs and two inner circumferential ribs. A plurality of rib sipes are disposed on at least one circumferential rib. The tire includes a plurality of curvilinear spline sipes, wherein each curvilinear spline sipe has multiple inflection points. At least one curvilinear spline sipe is disposed on an outer circumferential rib and at least one curvilinear spline sipe is disposed on a different circumferential rib. A localized depth of the at least one curvilinear spline sipe disposed on the outer circumferential rib varies in proportion to the distance from the rib sipes that intersect the at least one curvilinear spline sipe.

FIELD OF INVENTION

The present disclosure is directed to a vehicle tire tread. Moreparticularly the present disclosure is directed to a vehicle tire thathas wavy, serpentine, curvilinear, or spline features in an outercomponent, such as a tire tread. The tire may be pneumatic ornon-pneumatic.

BACKGROUND

Known tire treads have a variety of grooves and sipes. The grooves andsipes may vary in width, length, depth, and planar orientation.Modifying the width, length, depth, and planar orientation of thesefeatures will impact various properties of the tire, such as stiffnessand wear. Thus, the width, length, depth, and planar orientation ofthese features is modified to improve tire performance.

SUMMARY OF THE INVENTION

In one embodiment, a tire comprises a plurality of main circumferentialgrooves and a plurality of discrete road-contacting land portions. Thetire further includes a plurality of tread sipes, including at least onethree-dimensional circumferentially-oriented serpentine sipe thatextends predominately in the circumferential direction. Thecircumferentially-oriented serpentine sipe is disposed on a discreteroad-contacting land portion. The circumferentially-oriented serpentinesipe has a first axial position associated with a minimum axialdisplacement, and a second axial position associated with a maximumaxial displacement. The circumferentially-oriented serpentine sipefollows a serpentine path between the first and second axial positions.The circumferentially-oriented serpentine sipe has a first depth and asecond depth, the first depth being a minimum circumferentially-orientedserpentine sipe depth and the second depth being a maximumcircumferentially-oriented serpentine sipe depth. Thecircumferentially-oriented serpentine sipe follows a serpentine pathbetween the first and second depths. The first depth of thecircumferentially-oriented serpentine sipe is at least 10% greater thanthe depth of a tread sipe and the second depth of thecircumferentially-oriented serpentine sipe is at least 10% less than thedepth of a main circumferential groove. As one of ordinary skill in theart will understand, this tire is suitable for use in various types ofvehicles, and is particularly suitable for passenger vehicles and/orlight trucks.

In another embodiment, a tire comprises a first annular bead and asecond annular bead, and a body ply extending between the first annularbead and the second annular bead. The tire further includes acircumferential belt disposed radially outward of the body ply andextending axially across a portion of the body ply. The tire also has acircumferential tread disposed radially outward of the circumferentialbelt and extending axially across a portion of the body ply. A firstreinforcement ply is disposed radially between the circumferential treadand the circumferential belt and extends axially across a portion of thebody ply. The tire also includes a first sidewall extending between thefirst annular bead and a first shoulder, the first shoulder beingassociated with the circumferential tread, and a second sidewallextending between the second annular bead and a second shoulder, thesecond shoulder being associated with the circumferential tread. Thecircumferential tread further comprises at least three circumferentialgrooves that divide the circumferential tread into two outercircumferential ribs and two inner circumferential ribs. The tread alsoincludes a plurality of rib sipes disposed on at least onecircumferential rib, and a plurality of curvilinear spline sipes. Eachcurvilinear spline sipe has multiple inflection points. At least onecurvilinear spline sipe is disposed on an outer circumferential rib andat least one curvilinear spline sipe is disposed on a differentcircumferential rib. A localized depth of the at least one curvilinearspline sipe disposed on the outer circumferential rib varies inproportion to the distance from the rib sipes that intersect the atleast one curvilinear spline sipe. As one of ordinary skill in the artwill understand, this tire is suitable for use in various types ofvehicles, and is particularly suitable for passenger vehicles and/orlight trucks.

In yet another embodiment, a tire tread comprises at least two primarilystraight circumferential grooves, which extend continuously around thetire in a circumferential direction. The tire tread also has at leastthree circumferential ribs, which extend around the tire in thecircumferential direction. The at least three circumferential ribsinclude two outer circumferential ribs, each of which is disposedbetween an outer edge of the tire tread and an axially-outer edge of acircumferential groove. The at least three circumferential ribs furtherinclude at least one inner circumferential rib disposed betweenaxially-inner edges of at least two circumferential grooves. The tiretread further includes a first plurality of predominately-axial grooves,disposed in at least one outer circumferential rib, which extend from anouter edge of the tire tread to a circumferential groove. The tire treadalso has a second plurality of predominately-axial grooves, disposed onat least one inner circumferential rib, which extend across at least aportion of an inner circumferential rib. The tire tread further includesa first plurality of predominately-axial sipes, disposed on at least oneouter circumferential rib, which extend across at least a portion of theouter circumferential rib between an outer edge of the tire tread and acircumferential groove. The tire tread also has a second plurality ofpredominately-axial sipes, disposed on at least one innercircumferential rib, which extend across at least a portion of an innercircumferential rib. The tire tread further includes at least two narrowwavy circumferential grooves, disposed on at least two outercircumferential ribs, which extend around the tire tread in thecircumferential direction. The tire tread also includes at least onewavy circumferential sipe, disposed on at least one innercircumferential rib, which extends around the tire tread in thecircumferential direction. Additionally, the tire tread has a pluralityof shoulder grooves disposed along an outer edge of the tire treadbetween the wavy circumferential sipes and a sidewall, which extendpredominately circumferentially. The tire tread also includes aplurality of tie-bars, disposed in the first plurality ofpredominately-axial grooves, wherein the two narrow wavy circumferentialgrooves disposed on the outer circumferential ribs undulate axiallybetween an outer edge of the tire tread and an outer edge of acircumferential groove. The wavy circumferential sipe disposed on aninner circumferential rib undulates axially between the inner edges ofadjacent circumferential grooves. The depth of the narrow wavycircumferential grooves disposed on the outer circumferential ribsvaries in a curvilinear manner, such that the depth of the narrow wavycircumferential grooves increases as the circumferential distance fromthe narrow wavy circumferential groove to a predominately-axial sipeincreases. The width of each of the two narrow wavy circumferentialgrooves disposed on the outer circumferential ribs is greater than thewidth of the wavy circumferential sipe disposed on an innercircumferential rib. As one of ordinary skill in the art willunderstand, this tire tread is suitable for use in various types oftires, and is particularly suitable for passenger tires and/or lighttrucks.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, structures are illustrated that, togetherwith the detailed description provided below, describe exemplaryembodiments of the claimed invention. Like elements are identified withthe same reference numerals. It should be understood that elements shownas a single component may be replaced with multiple components, andelements shown as multiple components may be replaced with a singlecomponent. The drawings are not to scale and the proportion of certainelements may be exaggerated for the purpose of illustration.

FIG. 1 is a perspective view of one embodiment of a new tire;

FIG. 2 is a top plan view of the tire shown in FIG. 1;

FIG. 3a is a top plan view of the tire shown in FIG. 1 when the tiretread is 25% worn;

FIG. 3b is a top plan view of the tire shown in FIG. 1 when the tiretread is 50% worn;

FIG. 3c is a top plan view of the tire shown in FIG. 1 when the tiretread is 75% worn;

FIG. 4 is a side elevational cross-sectional view of the tire shown inFIG. 1;

FIG. 5 is a top plan view of an alternative embodiment of a new tire;

FIG. 6 is a side elevational cross-sectional view taken along line 6-6in FIG. 5;

FIG. 7 is a side elevational cross-sectional view of an alternativeembodiment of a new tire;

FIG. 8 is a side elevational cross-sectional view of another alternativeembodiment of a new tire;

FIG. 9 is a side elevational cross-sectional view of yet anotheralternative embodiment of a new tire;

FIG. 10 is a top plan view of still another alternative embodiment of anew tire tread;

FIG. 11 is a top plan view of an alternative embodiment of a new tire;

FIG. 12 is a top plan view of an alternative embodiment of a new tire;

FIG. 13 is a top plan view of an alternative embodiment of a new tire;and

FIG. 14 is a top plan view of an alternative embodiment of a new tire.

DETAILED DESCRIPTION

The following includes definitions of selected terms employed herein.The definitions include various examples and/or forms of components thatfall within the scope of a term and that may be used for implementation.The examples are not intended to be limiting. Both singular and pluralforms of terms may be within the definitions.

“Axial” and “axially” refer to a direction that is parallel to the axisof rotation of a tire.

“Circumferential” and “circumferentially” refer to a direction extendingalong the perimeter of the surface of the tread perpendicular to theaxial direction.

“Radial” and “radially” refer to a direction perpendicular to the axisof rotation of a tire.

“Sidewall” as used herein, refers to that portion of the tire betweenthe tread and the bead.

“Tread” as used herein, refers to that portion of the tire that comesinto contact with the road or ground under normal inflation and load.

While similar terms used in the following descriptions describe commontire components, it is understood that because the terms carry slightlydifferent connotations, one of ordinary skill in the art would notconsider any one of the following terms to be purely interchangeablewith another term used to describe a common tire component.

FIG. 1 is a perspective view of one embodiment of a tire 100. In FIG. 1,tire 100 is new. It is understood that the tread pattern on tire 100 isrepeated about the circumference of the tire tread, and the oppositeside is the same as that shown. FIG. 2 is an enlarged fragmentary frontelevational view of tire 100. Tire 100 will be described with referenceto both FIGS. 1 and 2.

A circumferential tread extends around the tire 100. Although only aportion of the circumferential tread can be seen in the figures, one ofordinary skill in the art will understand the tread pattern is repeatedthroughout the circumference of tire 100, and the opposite side of tire100 (not shown) is the same as the portion that is shown. As one ofordinary skill in the art will understand, tire 100 is suitable for usein various types of vehicles, and is particularly suitable for passengervehicles and/or light trucks.

Circumferential grooves 105 a-c divide the circumferential tread of thetire 100 into circumferential ribs 110 a-d. Both the ribs and groovesextend continuously around the tire in a circumferential direction. Ribs110 a and 110 d are outer circumferential ribs, and ribs 110 b and 110 care inner circumferential ribs. The outer circumferential ribs 110 a and110 d are disposed between an outer edge of the tire tread and theaxially-outer edges of circumferential grooves 105 a and 105 c. Theinner circumferential ribs 110 b and 110 c are disposed between theaxially-inner edges of circumferential grooves 105 a and 105 c. Whilefour circumferential ribs are shown in the illustrated embodiment, itshould be understood that any number of ribs may be employed.Additionally, while the circumferential grooves are shown as beingsubstantially straight in the illustrated embodiment, it should beunderstood that they may follow any pattern.

Ribs 110 a and 110 d contain a first plurality of predominately-axialgrooves 115. The grooves are predominately-axial because the axialdisplacement of the grooves is greater than the circumferentialdisplacement of the grooves. In alternative embodiments, the firstplurality of predominately-axial grooves may be replaced with transversegrooves disposed at any angle. In another alternative embodiment, thefirst plurality of predominately-axial grooves may be omitted entirely.

In one embodiment, the width of a groove is 1.524 mm. In otherembodiments, the width of the groove may be greater than 1.524 mmLikewise, the depth of a groove may vary between 0.10 mm and full treaddepth.

As shown, the width of the first plurality of predominately-axialgrooves 115 narrows near the axial-middle region of the rib. Thus, atleast one of the predominately-axial grooves narrows across a portion ofa circumferential rib. In an alternative embodiment, the first pluralityof predominately-axial grooves may vary in width at any given axialpoint. In another alternative embodiment, the width of the firstplurality of predominately-axial grooves is substantially constant.

The first plurality of predominately-axial grooves 115 follow acurvilinear path across ribs 110 a and 110 d. In an alternativeembodiment, the first plurality of predominately-axial grooves may besubstantially straight. As one of ordinary skill in the art willunderstand, the first plurality of predominately-axial grooves 115 maybe disposed on a single rib—inner or outer—or on multiple ribs. Inanother embodiment (not shown), the predominately-axial grooves on atleast two circumferential ribs align over at least one circumferentialgroove.

Ribs 110 a and 110 d also contain a second plurality ofpredominately-axial grooves 120. In alternative embodiments, the secondplurality of predominately-axial grooves may be replaced with transversegrooves disposed at any angle. In another alternative embodiment, thesecond plurality of predominately-axial grooves may be omitted entirely.

In the illustrated embodiment the width of the second plurality ofpredominately-axial grooves 120 narrows to a sipe near the axial-innerregion of the rib. In an alternative embodiment, the second plurality ofpredominately-axial grooves may vary in width at any given axial point.In another alternative embodiment, the width of the second plurality ofpredominately-axial grooves is substantially constant. As one ofordinary skill in the art will understand, the second plurality ofpredominately-axial grooves 120 may be disposed on a single rib—inner orouter—or on multiple ribs.

As shown, the second plurality of predominately-axial grooves 120follows a curvilinear path across the ribs. In an alternativeembodiment, the second plurality of predominately-axial grooves 120 issubstantially straight.

Ribs 110 a and 110 d contain a first plurality of predominately-axialsipes 135. The sipes are predominately-axial because the axialdisplacement of the sipes is greater than the circumferentialdisplacement of the sipes. In an alternative embodiment, the sipes maybe oriented at any angle. In other alternative embodiments, the sipesmay assume a variety of geometric patterns or orientations, including,without limitations, circular, curved, straight, diagonal, bent, zigzag,wavy forms. In general, the width of a sipe is 0.762 mm, but the widthmay vary between a smallest attainable manufacturing width and less thantwice the size of a standard sipe (1.524 mm). Additionally, the depth ofthe sipe may vary from 0.10 mm to full tread depth.

As shown, the sipes begin at circumferential groove 105 a and 105 c andalign with and widen into the second plurality of predominately-axialgrooves 120. The width of the first plurality of predominately-axialsipes 135 is substantially constant before widening into the secondplurality of predominately-axial grooves 120. The sipes follow acurvilinear path from the circumferential grooves and align with andwiden into the second plurality of predominately-axial grooves 120. Inalternative embodiments, the sipes follow a straight, angled, or bentpath. In another alternative embodiment, the first plurality ofpredominately-axial sipes may vary in width at any given axial point. Inyet another alternative embodiment, the first plurality ofpredominately-axial sipes 135 does not align with the second pluralityof predominately-axial grooves 120.

As one of ordinary skill in the art will understand, the first pluralityof predominately-axial sipes 135 may be disposed on a single rib—inneror outer—or on multiple ribs. In alternative embodiments, thepredominately-axial sipes extend across the tread in a curved, curly,sinusoidal, diagonal, straight, bent, or zigzag manner. In alternativeembodiments, the first plurality of predominately-axial sipes may bereplaced with transverse grooves disposed at any angle. In anotheralternative embodiment, the first plurality of predominately-axial sipesmay be omitted entirely.

Ribs 110 b and 110 c also contain a third plurality ofpredominately-axial grooves 125. As shown, the width of the thirdplurality of predominately-axial grooves 125 is substantially constant.The grooves follow a curvilinear path across ribs 110 b and 110 c. In analternative embodiment, the third plurality of predominately-axialgrooves may vary in width at any given axial point. As one of ordinaryskill in the art will understand, the third plurality ofpredominately-axial grooves 125 may be disposed on a single rib—inner orouter—or on multiple ribs. In alternative embodiments, the thirdplurality of predominately-axial grooves may be replaced with transversegrooves disposed at any angle. In another alternative embodiment, thethird plurality of predominately-axial grooves may be omitted entirely.

Ribs 110 b and 110 c contain a fourth plurality of predominately-axialgrooves 130. As shown, the fourth plurality of predominately-axialgrooves follow a curvilinear path across the ribs, and the width of thegrooves 130 narrows to a sipe near the axial-inner region of the rib. Inan alternative embodiment, the fourth plurality of predominately-axialgrooves may vary in width at any given axial point. In anotheralternative embodiment, the width of the fourth plurality ofpredominately-axial grooves is substantially constant. As one ofordinary skill in the art will understand, the fourth plurality ofpredominately-axial grooves 130 may be disposed on a single rib—inner orouter—or on multiple ribs. In alternative embodiments, the fourthplurality of predominately-axial grooves may be replaced with transversegrooves disposed at any angle. In another alternative embodiment, thefourth plurality of predominately-axial grooves may be omitted entirely.

Ribs 110 b and 110 c contain a second plurality of predominately-axialsipes 140. As shown, the sipes begin at circumferential groove 105 b andalign with and widen into the fourth plurality of predominately-axialgrooves 130. The width of the second plurality of predominately-axialsipes 140 is substantially constant before widening into the fourthplurality of predominately-axial grooves 130. The sipes follow acurvilinear path from circumferential groove 105 b and align with andwiden into the fourth plurality of predominately-axial grooves 130. Inalternative embodiments, the sipes follow a straight, angled, or bentpath. In another alternative embodiment, the second plurality ofpredominately-axial sipes may vary in width at any given axial point. Inyet another alternative embodiment, the second plurality ofpredominately-axial sipes 140 does not align with the fourth pluralityof predominately-axial grooves 120. As one of ordinary skill in the artwill understand, the second plurality of predominately-axial sipes 140may be disposed on a single rib—inner or outer—or on multiple ribs. Inan alternative embodiment, the second plurality of predominately-axialsipes may vary in width at any given axial point. In another alternativeembodiment, the second plurality of predominately-axial sipes 140 doesnot align with the fourth plurality of predominately-axial grooves 130.As one of ordinary skill in the art will understand, the secondplurality of predominately-axial sipes 140 may be disposed on a singlerib—inner or outer—or on multiple ribs. In alternative embodiments, thesecond plurality of predominately-axial sipes may be replaced withtransverse grooves disposed at any angle. In another alternativeembodiment, the second plurality of predominately-axial sipes may beomitted entirely.

Ribs 110 a and 110 d contain narrow wavy circumferential grooves 145.The width of the narrow wavy circumferential grooves is greater than thewidth of a sipe, but less than the width of circumferential grooves 105a-c. Apart from brief intersections with grooves or sipes, narrow wavycircumferential grooves 145 extend continuously around the tire in thecircumferential direction. Thus, the narrow wavy circumferential grooves145 extend substantially continuously around the tire in thecircumferential direction. As shown, the two narrow wavy circumferentialgrooves 145 undulate axially between an outer edge of the tire tread andan outer edge of a circumferential groove, 105 a and 105 c, withouttouching the edge of the tread or the circumferential grooves . Inalternative embodiments, the wavy circumferential grooves undulatesinusoidally, and they may touch the edge of the tread or the edge of acircumferential groove (for example, in a tangential manner). In anotheralternative embodiment, the frequency or the magnitude of the sinusoidalundulations varies.

In one embodiment, the depth of the wavy circumferential grooves 145 isequal to the depth of the first plurality of predominately-axial sipes140 at the location where the wavy circumferential grooves 145 intersectthe first plurality of predominately-axial sipes 140. In an additionalembodiment, the depth of the wavy circumferential grooves 145 does notexceed 40% of the depth of the circumferential grooves 105 a-d. In yetanother embodiment, the depth of the wavy circumferential grooves 145does not exceed 60% of the depth of the first plurality ofpredominately-axial grooves 115.

In additional alternative embodiments (not shown), ribs 110 a and 110 dalso contain at least one narrow circumferential groove disposed near anouter edge of a rib, so as to form a so-called sacrificial rib. In adifferent embodiment, two or more wavy circumferential sipes or groovesare disposed on the inner halves of the outer circumferential ribs.

Ribs 110 b and 110 c contain narrow wavy circumferential sipes 150. Thewidth of the narrow wavy circumferential sipes is greater than or equalto the width of a sipe, but less than the width of a narrow wavycircumferential groove 145. Apart from brief intersections with groovesor sipes, narrow wavy circumferential sipes 150 extend continuouslyaround the tire in the circumferential direction. Thus, the narrow wavycircumferential sipes 150 extend substantially continuously around thetire in the circumferential direction. As shown, the narrow wavycircumferential sipes 150 undulate axially between an axially-inner edgeof circumferential grooves 105 a and 105 c and circumferential groove105 b. The narrow wavy circumferential sipes 150 undulate axiallybetween the circumferential grooves without touching the edge of thecircumferential grooves. Thus, the narrow wavy circumferential sipes 150undulate axially between the edges of adjacent circumferential grooves.In alternative embodiments, the wavy circumferential grooves undulatesinusoidally, and they may touch the edge of a circumferential groove(for example, in a tangential manner). In additional alternativeembodiments, the frequency and/or the magnitude of the sinusoidalundulations varies. In another embodiment, the wavy circumferential sipedisposed on an inner circumferential rib is disposed on the middle thirdof the inner circumferential rib. In alternative embodiments, the narrowwavy circumferential sipes may be replaced with narrow circumferentialsipes. In another alternative embodiment, the narrow wavycircumferential grooves may be omitted entirely.

Tire 100 also contains a plurality of tie-bars 165. Tie-bars 165 aredisposed in the first plurality of predominately-axial grooves 115. Asone of ordinary skill in the art will understand, tie bars may bedisposed in other predominately-axial grooves. The tie bars increase thetread pattern's stiffness. In alternative embodiments, the firstplurality of tie-bars may be omitted entirely.

FIGS. 3a-c are top plan views of the tire shown in FIG. 1 as the tiretread is increasingly worn. FIG. 3a shows the tire at 25% wear, FIG. 3bshows the tire at 50% wear, and FIG. 3C shows the tire at 75% wear.

As shown in FIG. 3b , the width of the narrow wavy circumferentialgrooves 145 at 50% wear is greater than the width of the narrow wavycircumferential grooves 145 when the tire is new. Likewise, the widthsof the first plurality of predominately-axial grooves 115, secondplurality of predominately-axial grooves 120, fourth plurality ofpredominately-axial grooves 130, first plurality of predominately-axialsipes 135, and second plurality of predominately-axial sipes 140 at 50%wear is greater than the width of these features when the tire is new.As one of ordinary skill in the art will understand, the widths of anyof these features may be adjusted independently from any otheradjustment to the tire.

FIG. 4 is a side elevational cross-sectional view of the tire shown inFIG. 1. As shown, the first plurality of shoulder grooves 155 and secondplurality of shoulder grooves 160 connect at a common vertex, 165. Thefirst and second pluralities of shoulder grooves are separated by awedge 170.

FIG. 5 is a top plan view of an embodiment of a new tire 200. As one ofordinary skill in the art will understand, tire 200 is suitable for usein various types of vehicles, and is particularly suitable forhigh-performance passenger vehicle or light truck applications. Asshown, tire 200 contains a plurality of main circumferential grooves 205a-d and a plurality of discrete road-contacting land portions 210 a-e.As one of ordinary skill in the art will understand, the main grooves205 a-d can come in a variety of widths, may have different axialdisplacements, may curve, zigzag, or be straight, and may containfeatures such as chamfering, stone ejectors, or noise resonancereduction protrusions. Likewise, the discrete road-contacting landportions 210 a-e can come in a variety of widths and geometries. Theland portions may be continuous around the tire, or they may be dividedby various grooves or sipes.

As shown, tire 200 contains tread sipes 215 a-d. Tread sipes 215 aextend circumferentially along a scalloped path, tread sipes 215 bextend along a curved, diagonal path, and tread sipe 215 c extendscircumferentially down the center of the tread. In alternativeembodiments (not shown), tread sipes 215 a-c assume a curved, zigzag, orgeometric geometry.

As shown, tread sipe 215 d is a three-dimensionalcircumferentially-oriented serpentine sipe that extends predominately inthe circumferential direction. Line 6-6 represents the bottom of treadsipe 215 d. Tread sipe 215 d has a first axial position 220, which isassociated with a minimum axial displacement (the shortest axialdistance between a main groove and tread sipe 215 d). Tread sipe 215 dhas a second axial position 225, which is associated with a maximumaxial displacement (the longest axial distance between a main groove andtread sipe 215 d). In one embodiment, the axial distance between thefirst and second axial positions of tread sipe 215 d does not exceed 10%of the width of the tire tread. In another embodiment, the axialdistance between the first and second axial positions of tread sipe 215d does not exceed 25% of the width of the tire tread.

In the illustrated embodiment, the tread sipe 215 d is said to extendpredominately in the circumferential direction because thecircumferential displacement between the first and second axialpositions, 220 and 225, exceeds the axial displacement between the twopositions. As shown, the circumferentially-oriented serpentine treadsipe 215 d follows a serpentine path between the first and second axialpositions, 220 and 225. In another embodiment, the tread sipe extendspredominately in the circumferential direction—in other words, thecircumferential displacement between two inflection points typicallyexceeds the axial displacement between the same two inflection points.In such an embodiment, the circumferentially-oriented serpentine treadsipe also follows a serpentine path between the two inflection points.

Further, as shown, tread sipe 215 d is disposed on a single discreteroad-contacting land portion 210 e. In an alternative embodiment, treadsipe 215 d is disposed across multiple road-contacting land portions. Inanother embodiment, multiple three-dimensionalcircumferentially-oriented serpentine sipes are disposed on multipleroad-contacting land portions.

FIG. 6 is a side elevational cross-sectional view taken along line 6-6in FIG. 5. FIG. 6 shows how the depth of tread sipe 215 d varies over agiven circumferential displacement. As shown, tread sipe 215 d has afirst depth 230 and a second depth 235. The first depth 230 is a minimumsipe depth, which represents the shortest (shallowest) radial distancebetween the tread surface and the bottom of tread sipe 215 d. The seconddepth 235 is a maximum sipe depth, which represents the greatest(deepest) radial distance between the tread surface and the bottom oftread sipe 215 d. The first and second depths may be selected at anylocation. As shown, tread sipe 215 d follows a serpentine path betweenthe first and second depths, 230 and 235. In one embodiment, the firstdepth 230 is generally under a tread sipe. In an alternative embodiment,the first depth 230 is in substantial proximity (in the radialdirection) to a tread sipe because the distance between the first depth230 and the tread sipe is between 5-15% of the tread width.

In the embodiment shown in FIG. 6, the first depth 230 of tread sipe 215d is at least 10% greater than the depth of a typical tread sipe, andthe second depth 235 of tread sipe 215 d is at least 10% less than thedepth of a main groove 205 a-d. In another embodiment (not shown), thefirst depth 230 is at least 20% greater than the depth of a typicaltread sipe, and the second depth 235 is at least 20% less than the depthof a main groove 205 a-d.

While only the depth of the first circumferentially oriented sipe 215 dis shown and discussed, it should be understood that the othercircumferentially oriented sipes in the other ribs may have the samevariable depth.

FIG. 7 is a side elevational cross-sectional view of an alternativeembodiment of a new tire. In the embodiment shown in FIG. 7, tread sipe215 d has a first depth 230 and second depth 235 that are generally thesame as the first and second depths shown in FIG. 6. In addition, asshown in FIG. 7, this alternative embodiment of tread sipe 215 d has athird depth 240 and fourth depth 245. Third depth 240 is greater(deeper) than the first depth 230 but less (shallower) than the seconddepth 235. Fourth depth 245 is greater (deeper) than the third depth 240but less (shallower) than the second depth 235. Thecircumferentially-oriented serpentine tread sipe 215 d follows aserpentine path in the radial plane between the first, second, third,and fourth depths, 230, 235, 240, and 245.

FIG. 8 is a side elevational cross-sectional view of another alternativeembodiment of a new tire. In the embodiment shown in FIG. 8, tread sipe215 d has a first depth 230 and second depth 235 that are generally thesame as the first and second depths shown in FIG. 6. In addition, asshown in FIG. 8, this alternative embodiment of tread sipe 215 d followsa diagonal path when viewed in the radial plane. As shown, the diagonalpath corresponds to three sides of a trapezoid because it contains twoangled portions of varying depth and one straight portion of constantdepth. In another embodiment (not shown), the diagonal path containsmultiple slopes and multiple lengths. In a different embodiment (alsonot shown), the diagonal path connects to third and fourth depths.

FIG. 9 is a side elevational cross-sectional view of yet anotheralternative embodiment of a new tire. In the embodiment shown in FIG. 9,tread sipe 215 d has a first depth 230 and second depth 235 that aregenerally the same as the first and second depths shown in FIG. 6. Inaddition, as shown in FIG. 9, this alternative embodiment of tread sipe215 d follows a diagonal or saw-toothed path when viewed in the radialplane. As shown, the diagonal path contains no rounded edges, but aperson of ordinary skill in the art would understand that the edges maybe slightly rounded. In another embodiment (not shown), the diagonalpath contains multiple slopes and multiple lengths. In a differentembodiment (also not shown), the diagonal path connects to third andfourth depths.

FIG. 10 is a top plan view of another embodiment of a new tire tread300. In one application, the tread shown in FIG. 10 is for use on apneumatic tire comprising a first annular bead and a second annularbead, a body ply extending between the first annular bead and the secondannular bead, a circumferential belt disposed radially outward of thebody ply and extending axially across a portion of the body ply, acircumferential tread disposed radially outward of the circumferentialbelt and extending axially across a portion of the body ply, a firstreinforcement ply disposed radially between the circumferential treadand the circumferential belt and extending axially across a portion ofthe body ply, a first sidewall extending between the first annular beadand a first shoulder, the first shoulder being associated with thecircumferential tread, and a second sidewall extending between thesecond annular bead and a second shoulder, the second shoulder beingassociated with the circumferential tread. In another application (notshown), the tread may be used on a non-pneumatic tire or wheel, whichmay not have certain components present in a pneumatic tire. In yetanother application (also not shown), the tread is a retread.

As shown in FIG. 10, the circumferential tread 300 contains fivecircumferential grooves 305 a-e. The circumferential grooves 305 a-edivide the circumferential tread into two outer circumferential ribs anda middle rib. The outer circumferential ribs have two rows of treadblocks, 310 a, 310 b, 315 a and 315 b. The middle rib has two rows oftread blocks 320 a and 320 b. In alternative embodiments (not shown),the tread has four, five, or six circumferential grooves and five, six,or seven ribs.

As shown in FIG. 10, the circumferential tread 300 also contains a firstplurality of rib sipes 325. The rib sipes 325 are disposed on every rowof tread blocks on all three ribs. In alternative embodiments (notshown), the rib sipes are not disposed on every row of tread blocks orevery rib. In an additional embodiment (also not shown), the treadfeatures several pluralities of rib sipes.

As shown in FIG. 10, the circumferential tread 300 also contains aplurality of curvilinear spline sipes 330. One curvilinear spline sipeis disposed on an outer row of tread blocks 310 a, and at least oneother curvilinear spline sipe is disposed on a different circumferentialrib (e.g., 310 b). In a specific embodiment (shown in FIG. 10), thetread only has two curvilinear spline sipes, both of which are disposedon the outer circumferential ribs.

The curvilinear spline sipes 330 intersect the rib sipes 325. It isunderstood that the curvilinear spline sipes 330 are substantiallycontinuous even though they may intersect various features such as ribsipes 325 or rib grooves 335. As shown, the curvilinear spline sipe 330disposed on the outer circumferential rib follows asubstantially-continuous sinusoidal circumferential path around the tirewhen the tire is new.

In one embodiment, the curvilinear spline sipe 330 becomes discontinuousas the tire wears. In one version of this particular embodiment, thecurvilinear spline sipe disposed on the outer circumferential ribfollows a non-continuous circumferential path when the circumferentialtread depth is reduced by 75%. In another embodiment (not shown), thedepth of the plurality of curvilinear spline sipes is configured so thatthe circumferential tread void decreases between 2 and 10% when thecircumferential tread depth is reduced by 50%. In a different embodiment(also not shown), the depth of the plurality of curvilinear spline sipesis configured so that the circumferential tread void decreases between 5and 12% when the circumferential tread depth is reduced by 75%.

In one embodiment (shown in FIG. 13), the curvilinear spline sipes 330have multiple axial inflection points 340 when viewed in thecircumferential plane. Additionally, the curvilinear spline sipes 330have multiple radial inflection points when viewed in the radial plane(not shown in FIG. 10).

Each curvilinear spline sipe 330 has a depth that varies based on itsproximity to a sipe. The localized depth of the curvilinear spline sipe330 is the depth of the sipe at any given point on the tread. The depthof the spline sipe varies in proportion to the distance from the ribsipes that intersect the at least one curvilinear spline sipe. Thus, thedepth of the curvilinear spline sipe 330 will increase as the distancefrom a rib sipe increases. In one embodiment, the depth of a curvilinearspline sipe 330 increases in direct proportion to the distance from arib sipe. In another embodiment, the depth of a curvilinear spline sipe330 increases as a mathematical function of the distance from a ribsipe.

In the embodiment shown in FIG. 10, the circumferential tread 300 iswell suited for use as a snow tire in passenger and light truckapplications. The circumferential tread, however, has uses beyondpassenger and light truck applications. One such exemplary use includes,without limitation, truck-and-bus-radial tire applications.

In a different embodiment (not shown), the circumferential tread furthercomprises a narrow curvilinear spline groove. The narrow curvilinearspline groove follows a sinusoidal circumferential path around the tire.One of ordinary skill in the art would understand that a narrowcurvilinear spline groove is wider than a sipe but narrower than acircumferential groove.

FIG. 11 is a top plan view of an alternative embodiment of a new tire.In the embodiment shown in FIG. 11, curvilinear spline sipe 330 followsa straight path in the circumferential plane.

FIG. 12 is a top plan view of an alternative embodiment of a new tire.In the embodiment shown in FIG. 12, curvilinear spline sipe 330 followsa circumferential path that contains alternating straight and curvedsegments.

FIG. 13 is a top plan view of another alternative embodiment of a newtire. In the embodiment shown in FIG. 13, curvilinear spline sipe 330follows a curved circumferential path that contains multiple axialinflection points.

FIG. 14 is a top plan view of yet another alternative embodiment of anew tire. In the embodiment shown in FIG. 14, curvilinear spline sipe330 follows a zigzag path in the circumferential plane.

As one of ordinary skill in the art would understand, the tireembodiments described in this disclosure may be configured for use on avehicle selected from the group consisting of motorcycles, golf carts,scooters, military vehicles, passenger vehicles, hybrid vehicles,high-performance vehicles, sport-utility vehicles, light trucks, heavytrucks, heavy-duty vehicles, and buses. One of ordinary skill in the artwould also understand that the embodiments described in this disclosuremay be utilized with a variety of tread patterns, including, withoutlimitation, symmetrical, asymmetrical, directional, studded, andstud-free tread patterns. One of ordinary skill in the art would alsounderstand that the embodiments described in this disclosure may beutilized, without limitation, in high-performance, winter, all-season,touring, non-pneumatic, and retread tire applications.

To the extent that the term “includes” or “including” is used in thespecification or the claims, it is intended to be inclusive in a mannersimilar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “or” is employed (e.g., A or B) it is intended to mean “Aor B or both.” When the applicants intend to indicate “only A or B butnot both” then the term “only A or B but not both” will be employed.Thus, use of the term “or” herein is the inclusive, and not theexclusive use. See, Bryan A. Garner, A Dictionary of Modern Legal Usage624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into”are used in the specification or the claims, it is intended toadditionally mean “on” or “onto.” Furthermore, to the extent the term“connect” is used in the specification or claims, it is intended to meannot only “directly connected to,” but also “indirectly connected to”such as connected through another component or components.

While the present disclosure has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. Therefore, the disclosure, in its broaderaspects, is not limited to the specific details, the representativeapparatus and method, and illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of the applicant's general inventive concept.

What is claimed is:
 1. A tire comprising: a circumferential tread; aplurality of tread sipes, including at least one three-dimensionalcircumferentially-oriented serpentine sipe that extends predominately ina circumferential direction, the circumferentially-oriented serpentinesipe being disposed on the circumferential tread, wherein thecircumferentially-oriented serpentine sipe has a first axial positionassociated with a minimum axial displacement, a second axial positionassociated with a maximum axial displacement, and thecircumferentially-oriented serpentine sipe follows a serpentine pathbetween the first and second axial positions, wherein thecircumferentially-oriented serpentine sipe has a first depth and asecond depth, the first depth being a minimum circumferentially-orientedserpentine sipe depth and the second depth being a maximumcircumferentially-oriented serpentine sipe depth, wherein thecircumferentially-oriented serpentine sipe has a third depth which isgreater than the first depth but less than the second depth, wherein thecircumferentially-oriented serpentine sipe has a fourth depth which isgreater than the third depth but less than the second depth, wherein thecircumferentially-oriented serpentine sipe follows a serpentine pathbetween the first and second depths, and wherein the first depth of thecircumferentially-oriented serpentine sipe and the second depth of thecircumferentially-oriented serpentine sipe is between 0.10 mm and fulltread depth.
 2. The tire of claim 1, wherein thecircumferentially-oriented serpentine sipe follows a serpentine path ina radial plane between the second and third depths.
 3. The tire of claim1, wherein the circumferentially-oriented serpentine sipe follows aserpentine path in the radial plane between the third and fourth depths.4. The tire of claim 1, wherein the axial distance between the first andsecond axial positions of the circumferentially-oriented serpentine sipedoes not exceed 10% of the width of the tire.
 5. The tire of claim 1,further comprising: a first annular bead and a second annular bead; abody ply extending between the first annular bead and the second annularbead; a circumferential belt disposed radially outward of the body plyand extending axially across a portion of the body ply; a first sidewallextending between the first annular bead and a first shoulder, the firstshoulder being associated with the circumferential tread; and a secondsidewall extending between the second annular bead and a secondshoulder, the second shoulder being associated with the circumferentialtread.
 6. The tire of claim 1, wherein the circumferential treadincludes at least three circumferential grooves that divide thecircumferential tread into two outer circumferential ribs and two innercircumferential ribs.
 7. The tire of claim 6, wherein thecircumferentially-oriented serpentine sipe is disposed on one of the twoouter circumferential ribs.
 8. The tire of claim 1, wherein thecircumferentially-oriented serpentine sipe follows asubstantially-continuous sinusoidal circumferential path around the tirewhen the tire is new.
 9. The tire of claim 8, wherein thecircumferentially-oriented serpentine sipe follows a non-continuouscircumferential path when the circumferential tread depth is reduced by75%.
 10. The tire of claim 1, wherein the depth of thecircumferentially-oriented serpentine sipe is configured so that acircumferential tread void decreases between 2 and 10% when thecircumferential tread depth is reduced by 50%.
 11. The tire of claim 1,wherein the depth of the circumferentially-oriented serpentine sipe isconfigured so that a circumferential tread void decreases between 5 and12% when the circumferential tread depth is reduced by 75%.